Washing machine and controlling method for the same

ABSTRACT

The present invention relates to a washing machine having a shortened washing time and a method of controlling the washing machine. A method of controlling a washing machine according to an exemplary embodiment of the present invention includes: a water supply step of supplying washing water into a tub; a steam step of spraying steam into a drum disposed in the tub; and a centrifugal washing step of circulating the washing water in the tub and of rotating the drum such that laundry attachs to the drum.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority benefit of Korean Patent Application No. 10-2013-0084820, filed on Jul. 18, 2013, the disclosure of which is incorporated herein by reference in its entirety.

BACKGROUND

1. Field of the Disclosure

The present invention relates to a washing machine and a control method thereof, particularly a washing machine that has a shortened washing time and a method of controlling the washing machine.

2. Description of the Related Art

In general, a washing machine is an apparatus that uses water, detergent, and mechanical action to wash, for example, clothing, bed linen, etc. (hereinafter referred to as ‘laundry’) through the process of wash, rinse, and spin cycles to remove contaminants from the laundry.

The washing machine largely falls into an agitator type washing machine, a pulsator type washing machine, and a drum type washing machine.

The agitator type washes laundry by rotating a washing bar, which protrudes at the center in a tub, to the left and right, the pulsator type washes laundry, using friction force between water currents and the laundry by turning disc-shaped rotary blades, which are formed on the bottom of a tub, to the left and right, and the drum type washes laundry by rotating a drum with water, a detergent, and laundry therein.

In the drum washing machine, a tub that receives washing water is disposed in a cabinet forming the external appearance, a drum that receives laundry is disposed in the tub, a driving unit for rotating the drum is disposed on the rear side of the tub, and a drive shaft connected to the rear side of the drum through the tub is connected to the driving unit. A lifter is disposed in the drum, and it pushes up laundry, when the drum rotates.

It is required for the drum washing machine to reduce the washing time and the use of wash and electricity.

SUMMARY

An object of the present invention is to provide a washing machine having a shortened washing time and improved washing performance, and a method of controlling the washing machine.

Another object of the present invention is to provide a washing machine using less water and electricity and having improve washing performance, and a method of controlling the washing machine.

The objects of the present invention are not limited to those described above and other objects may be made apparent to those skilled in the art from the following description.

In order to achieve the objects, a method of controlling a washing machine according to an exemplary embodiment of the present invention includes: a water supply step of supplying washing water into a tub; a steam step of spraying steam into a drum disposed in the tub; and a centrifugal washing step of circulating the washing water in the tub and of rotating the drum such that laundry attachs to the drum.

In order to achieve the objects, a washing machine according to an exemplary embodiment of the preset invention includes: a tub that receives washing water; a drum that is disposed in the tub and rotates with laundry therein; a driving unit that rotates the drum; a water supply unit that adjusts inflow of washing water from an external water source; a steam unit that generates steam and sprays the steam into the tub; a pump that pumps out the washing water in the tub and circulates the washing water into the tub; and a control unit that controls the driving unit, the water supply unit, and the pump, in which the control unit performs: a water supply step of supplying washing water into the tub by operating the water supply unit; a steam step of spraying steam into the drum by operating the steam unit; and a centrifugal washing step of rotating the rum such that laundry attachs to the drum by operating the driving unit and of circulating the washing water in the tub by operating the pump.

The details of other exemplary embodiments are included in the following detailed description and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a perspective view showing a washing machine according to an exemplary embodiment of the present invention;

FIG. 2 is a perspective view showing the internal structure of the washing machine shown in FIG. 1;

FIG. 3 is a partial cross-sectional view of the washing machine shown in FIG. 1;

FIG. 4 is a front view showing the internal structure of the washing machine shown in FIG. 1;

FIG. 5 is a block diagram illustrating the washing machine according to an exemplary embodiment of the present invention;

FIG. 6 is a flowchart illustrating a method of controlling a washing machine according to an exemplary embodiment of the present invention;

FIG. 7 is a partial detailed block diagram illustrating the washing machine according to an exemplary embodiment of the present invention;

FIG. 8 is a partial detailed flowchart illustrating a method of controlling a washing machine according to an exemplary embodiment of the present invention; and

FIG. 9 is a view showing a change in actual rotation speed of a drum and the result of applying a low band filter in the method of controlling a washing machine illustrated in FIG. 8.

DETAILED DESCRIPTION OF THE EMBODIMENT

The advantages and features of the present invention, and methods of achieving them will be clear by referring to the exemplary embodiments that will be describe hereafter in detail with reference to the accompanying drawings. However, the present invention is not limited to the exemplary embodiments described hereafter and may be implemented in various ways, and the exemplary embodiments are provided to complete the description of the present invention and let those skilled in the art completely know the scope of the present invention and the present invention is defined by claims. Like reference numerals indicate like components throughout the specification.

Hereinafter, the present invention will be described with reference to the drawings illustrating a washing machine and a method of controlling the washing machine according to exemplary embodiments of the present invention.

FIG. 1 is a perspective view showing a washing machine according to an exemplary embodiment of the present invention, FIG. 2 is a perspective view showing the internal structure of the washing machine shown in FIG. 1, FIG. 3 is a partial cross-sectional view of the washing machine shown in FIG. 1, and FIG. 4 is a front view showing the internal structure of the washing machine shown in FIG. 1.

A washing machine 100 according to an exemplary embodiment of the present invention includes a cabinet 111 that forms the external appearance, a tub 122 that receives washing water, a drum 124 that is disposed in the tub and rotates with laundry therein, a driving unit 113 that rotates the drum, a water supply unit 131 that adjusts inflow of washing water from an external water source, a steam unit 145 that generates steam, a detergent box 133 that receives a washing detergent and in which washing water and the washing detergent are mixed, and a pump 136 that pumps out the washing water in the tub and circulates it into the tub.

The cabinet 111 forms the external appearance of the washing machine 100. The tub 122 is disposed in the cabinet 111. The cabinet 111 has a laundry hole 120 through which laundry is put in/out. A door 112 that can turn is disposed on the front side of the cabinet 111 to be able to open/close the laundry hole 120. A control panel 114 that receives orders from a user and displays the information on various states of the washing machine 100 is disposed on the cabinet 111. The detergent box 133 that receives detergents such as a washing detergent, a rinsing detergent, or a bleach and can be drawn in/out is disposed inside the cabinet 111.

The tub 122 disposed in the cabinet 111 can absorb a shock with a spring (not shown) and a damper (not shown). The tub 122 receives washing water. The drum 124 is disposed in the tub 122.

The tub 122 may have a water level sensor 121 that senses the level of the washing water in the tub. The water level sensor 121 may be implemented in various ways, and in this exemplary embodiment, the level of the washing water is measured on the basis of a change in capacitance by changing the gap between electrodes, using an air pressure that changes with the level of the washing water. A heater 143 for heating washing water may be disposed in the tub 122.

The drum 124 rotates with laundry therein. The drum 124 has a plurality of holes 124 b for passing washing water. A lifter 124 a that pushes up laundry to a predetermined height, when the drum 124 rotates may be disposed in the drum 124. The drum 124 is rotated by a rotational force from the driving unit 113.

The drum 124 is not disposed completely horizontally, but may be disposed with a predetermined inclination such that the rear of the drum 124 is under the horizontality.

A gasket 128 is disposed between the tub 122 and the cabinet 111 and seals the tub 122 and the cabinet 111. The gasket 128 is disposed between the inlet of the tub 122 and the laundry hole 120. The gasket 128 attenuates a shock transmitted to the door 112, when the drum 124 rotates, and it prevents the washing water in the tub 122 from leaking outside.

The gasket 128 may be made one material, but the portion coupled to the tub 122 is made of a hard material to ensure strength for coupling to the tub 122 and sufficient rigidity. The portion coupled to the cabinet 111 may be made of an elastic material to attenuate vibration transmitted to the cabinet 111 from the tub 122.

The gasket 128 may have a spray nozzle 151 and a circulating nozzle 139 for spraying washing water into the drum 124, and a steam nozzle 152 for spraying steam into the drum 124.

The driving unit 113 rotates the drum 124. The driving unit 113 can rotate the drum 124 at various speeds or in various directions. The driving unit 113 may be composed of a motor, a switching element for controlling the motor, and a clutch. The driving unit 113 may include a sensor that senses the actual rotation speed of the drum 124.

The detergent box 133 receives detergents such as a washing detergent, a rinsing detergent, and a bleach. The detergent box 133 may be drawn in/out through the front of the cabinet 111. The detergent in the detergent box 133 is mixed with washing water and flows into the tub 112, when the washing water is supplied. The detergent box 133 may be divided into a portion for receiving a washing, a portion for receiving a rinsing detergent, and a portion for receiving a bleach.

The water supply unit 131 that adjusts inflow of washing water from an external water source, a first water supply hose 131 a, a second water supply hose 131 b, and a third water supply hose 131 c that are connected with the water supply unit 131 and guide the washing water supplied from an external water source to the detergent box 133 in accordance with operation of the water supply unit 131, a fourth water supply hose 131 d that is connected with the water supply unit 131 and guides the washing water supplied from the external water source to the spray nozzle 151 in accordance with operation of the water supply unit 131, and a fifth water supply hose 131 e that is connected with the water supply unit 131 and guides the washing water supplied from the external water source to the steam unit 145 in accordance with operation of the water supply unit 131 are disposed in the cabinet 111. Further, a water supply pipe 134 for delivering the washing water mixed with a detergent in the detergent box 133 into the tub 122 may be disposed in the cabinet 111.

The water supply unit 131 is connected with the water supply hose 130 connected with the external water source and adjusts inflow of the washing water supplied from the external source. The water supply unit 131 distributes the washing water supplied from the external source so that the washing water is supplied to at least one of the first water supply hose 131 a to the fifth water supply hose 131 e. The water supply unit 131 may be a vario module that can distribute washing water from one inlet to a plurality of outlets and it may be composed of a plurality of valves, depending on exemplary embodiments.

When the water supply unit 131 supplies washing water to the first water supply hose 131 a, the washing water supplied to the first water supply hose 131 a is mixed with a washing detergent through the part receiving a washing detergent in the detergent box 133 and then supplied into the tub 122 through the water supply pipe 134.

When the water supply unit 131 supplies washing water to the second water supply hose 131 b, the washing water supplied to the second water supply hose 131 b passes through the detergent box 133 without being mixed with a detergent in the detergent box 133 and is then supplied into the tub 122 through the water supply pipe 134.

When the water supply unit 131 supplies washing water to the third water supply hose 131 c, the washing water supplied to the first water supply hose 131 a is mixed with a bleach through the part receiving the bleach in the detergent box 133 and then supplied into the tub 122 through the water supply pipe 134.

When the water supply unit 131 supplies washing water to the fourth water supply hose 131 d, the washing water supplied from the external water source is sprayed into the drum 124 through the spray nozzle 151.

When the water supply unit 131 supplies washing water to the fifth water supply hose 131 e, the washing water supplied to the fifth water supply hose 131 e is heated in the steam unit 145. The steam unit 145 generates steam by heating the washing water. The steam generated by the steam unit 145 is supplied to the steam nozzle 152 through a steam supply hose 130 and sprayed into the drum 124 through the steam nozzle 152.

A flowmeter 142 is disposed in the supply hose 130 connecting the external water source with the water supply unit 131. The flowmeter 142 measures the flow rate of the washing water passing through the supply hose 130.

A drain pipe 135 through which the washing water in the tub 122 is discharged, the pump 136 that pumps out the washing water in the tub 122, a circulating hose 137 that is connected with the circulating nozzle 139 so that washing water is circulated and sprayed into the drum 124, and a drain hose 138 through which washing water is discharged to the outside are disposed in the cabinet 111.

The pump 136 pumps out the washing water in the tub 122. The pump 136 discharges the washing water, which is discharged from the tub 122 through the drain pipe 135, to the outside through the drain hose 138 or circulates the washing water into the tub 122 through the circulating hose 137. The pump 136 may be composed of a circulating pump and a drain pump and they may be connected with the circulating hose 137 and the drain hose 138, depending on exemplary embodiments.

The circulating hose 137 connects the pump 136 with the circulating nozzle 139. The washing water pumped out of the tub 122 by the pump 136 is sprayed into the drum 124 through the circulating hose 137 by the circulating nozzle 139.

The control panel 114 may have an input section 114 b through which washing course selection, the operation time of cycles, and various operation orders such as scheduling by a user are inputted, and a display section 114 a that displays the operation state of the washing machine 100.

Based on the types or functions of laundry, the washing course includes, other than a ordinary course, a lingerie/wool course, a boiling course, a speed wash course, a functional cloth course, a laundry protection course, a silent course, and an energy saving course etc. The operation of the washing machine 100 is divided into a washing cycle, a rinsing cycle, and a spinning cycle, and a water supply step, a washing step, a rinsing step, a draining step, a spinning step, or a drying step is performed in each of the cycles.

The spray nozzle 151 is disposed in the gasket 128 and sprays washing water into the drum 124. The spray nozzle 151 is disposed close to the steam nozzle 127. The spray nozzle 151 is connected with the fourth water supply hose 159 and sprays the washing water, which is supplied from the external water source, into the drum 124.

The spray nozzle 151 may be disposed at the top of the gasket 128, and it may be disposed at various positions, for example, on the bottom of the gasket 128, between the gasket 128 and the cabinet 111, or on the cabinet 111 or the tub 122, depending on the exemplary embodiments.

The spray nozzle may be a whirling nozzle that discharges washing water with a vortex, to the side or the rear of the drum 124.

The whirling nozzle is a nozzle that makes translation and circular movement of washing water. The whirling nozzle may be implemented in various types and it may have a plurality of curved channels to make a vortex in the washing water passing through the channel and spray it into the drum 124.

The steam nozzle 152 is disposed in the gasket 128 and sprays steam into the drum 124. The steam nozzle 152 is connected with the steam hose 146 and sprays the steam generated by the steam unit 145 into the drum 124.

The steam nozzle 152 is disposed close to the spray nozzle 151 at the top of the gasket 128. Depending on exemplary embodiments, the steam nozzle 152 may be disposed at various positions, for example, on the bottom of the gasket 128, between the gasket 128 and the cabinet 111, or on the cabinet 111 or the tub 122.

The circulating nozzle 139 is disposed in the gasket 128 and sprays washing water into the drum 124. The circulating nozzle 139 is connected with the circulating hose 137 and sprays the washing water circulated by the pump 136 into the drum 124. The circulating nozzle 139 may be formed integrally with the gasket 128.

The circulating nozzle 139 may be disposed under the rotary shaft of the drum 124 and spray washing water upward. A plurality of circulating nozzles 139 may be provided and two circulating nozzles may be disposed at both sides on the bottom of the gasket 128. A first circulating nozzle 139 a may be disposed at the left side on the bottom of the gasket 128 and spray washing water upward to the right side in the drum 124 and a second circulating nozzle 139 b may be disposed at the right side on the bottom of the gasket 128 and spray washing water upward to the left side in the drum 124.

When a plurality of circulating nozzles 139 is provided, a plurality of circulating nozzles 137 is provided, in which the first circulating hose 137 a may be connected with the first circulating nozzle 139 a and the second circulating hose 137 b may be connected with the second circulating nozzle 139 b.

The washing water in the drum 124 moves to the pump 136 through the drain pipe 135 of the tub 122. The pump 136 pumps the washing water to the circulating nozzle 139 through the circulating hose 137. The washing water is sprayed into the drum 124 through the circulating nozzle 139 and flows into the drum 122.

A balancer 126 is disposed around the drum 124 and maintains the center of gravity of the drum 124, when laundry is concentrated to a side. When the drum rotates with laundry concentrated on a side, vibration and noise are generated by unbalance that the geometric center of the rotary shaft of the drum 124 and the actual center of gravity are not matched. The balancer 126 reduces the unbalance of the drum 124 by making the actual center of gravity of the drum 124 close to the rotation center.

The balancer 126 may be disposed at the front portion and/or the rear portion of the drum 124, and it is on the front of the drum 124 in this exemplary embodiment. Since the laundry in the drum 124 is usually concentrated inside the drum 124, that is, at the rear portion of the drum 124, when the drum 124 rotates, the balancer 126 may be disposed on the front portion of the drum 124 to make balance with the laundry concentrated at the rear portion in the drum 124.

The balancer 126 includes a material having predetermined weight therein so that the center of gravity can move, and it includes a path through which the material can circumferentially move. The internal material of the balancer 126 is arranged to move opposite to the center of gravity of laundry to make the center of gravity of the drum 124 close to the rotation center.

The balancer may be a liquid balancer including liquid having predetermined weight therein or a ball balancer including a ball having predetermined weight. The balancer 126 is filled with a filler fluid together with a ball in this exemplary embodiment.

FIG. 5 is a block diagram illustrating the washing machine according to an exemplary embodiment of the present invention.

The control unit 141 controls the entire operation of the washing machine in accordance with the operation orders that the input unit 114 receives. The control unit 141 may be disposed in the control panel 114. It may be composed of a microcomputer controlling the operation of the washing machine, a memory, and other electronic components. The control unit 141 determines whether the cycles are performed, whether the operations such as water supplying, washing rinsing, draining, spinning, and drying are performed in each cycle, and the number of repetition, and performs them, in accordance with the washing courses selected by a user.

The control unit 141 receives and processes the flow rate of washing water measured by the flowmeter 142. The control unit 141 receives and processes the rotation speed of the drum 124 measured by the driving unit 113. The control unity 141 receives operation orders from the input unit 114 b and makes the display unit 114 a display the operation state of the washing machine 100. The control unit 141 controls the water supply unit 131, the driving unit 113, the pump 136, and the steam unit 145 in accordance with the selected courses or other operation orders.

FIG. 6 is a flowchart illustrating a method of controlling a washing machine according to an exemplary embodiment of the present invention.

A method of controlling a washing machine according to an exemplary embodiment of the present invention may be used, when a user selects centrifugal washing through the input unit 114 b of the control panel 114 or when an order for performing centrifugal washing is inputted to the control unit 141 in accordance with input or determination by a user. Further, general washing courses may be the washing methods to be described below, depending on exemplary embodiments.

A step of sensing the laundry amount 211 is a step of sensing the amount of laundry (hereafter, referred to as ‘laundry amount’) in the drum 124. In the step of sensing the laundry amount 211, the laundry amount can be measured in various methods, and in this exemplary embodiment, it is measured in a way that the control unit 141 activates the driving unit 112 to rotate the drum 124 for a predetermined time at a predetermined speed and then measures a deceleration time. The longer the deceleration time of the drum 124, the higher the level of the laundry amount.

Depending on exemplary embodiments, the control unit 141 may calculate the laundry amount by measuring the acceleration time or the acceleration force when the drum 124 is accelerated. The control unit 141 determines the amount of washing water to be supplied into the tub 122 in a water supply step 211 and the amount of washing water to be supplied into the tub 122 from the external water source in a centrifugal washing step 216, in accordance with the sensed laundry amount. Further, the control unit 141 can determine the time for performing the centrifugal washing step 216 in accordance with the sensed laundry amount.

The control unit 124 perform the water supply step 212, after finishing the laundry amount sensing step by stopping the drum 124.

The water supply step 212 is a step of supplying washing water into the tub 122. In the water supply step 212, washing water not mixed with a washing detergent and washing water mixed with a washing detergent may be simultaneously or sequentially supplied into the tub 122. In this exemplary embodiment, the washing water not mixed with a washing detergent and the washing water mixed with a washing detergent are alternately supplied.

In the water supply step 212, the control unit 141 makes washing water be supplied to the detergent box 133 through the first water supply hose 131 a and/or the second water supply hose 131 b by intermittently or continuously operating the water supply unit 131.

The control unit 141 makes washing water be supplied to the detergent box 133 through the second water supply hose 131 b by controlling the water supply unit 131. The washing water supplied to the detergent box 133 through the second water supply hose 131 b passes through the detergent box 133, without being mixed with a detergent in the detergent box 133, and is then supplied into the tub 122 through the water supply pipe 134. The control unit 141 intermittently or continuously controls the water supply unit 131 so that the washing water not mixed with a detergent can be intermittently or continuously supplied into the tub 122.

The control unit 141 makes washing water be supplied to the detergent box 133 through the first water supply hose 131 a by controlling the water supply unit 131. The washing water supplied to the detergent box 133 through the first water supply hose 131 b is mixed with a washing detergent through the part receiving the washing detergent in the detergent box 133 and then supplied into the tub 122 through the water supply pipe 134. The control unit 141 intermittently or continuously controls the water supply unit 131 so that the washing water mixed with a detergent can be intermittently or continuously supplied into the tub 122.

Depending on exemplary embodiments, the control unit 141 can make washing water be sprayed into the drum 124 through the spray nozzle 151 by making the washing water supplied from the external water source through the fourth water supply hose 131 d flow to the spray nozzle 151 by controlling the water supply unit 131. In the water supply step 212, the control unit 141 may intermittently operate the water supply unit 131 so that washing water is intermittently sprayed through the spray nozzle 151.

In the water supply step 212, the desired water level that is the amount of the washing water flowing into the tub 122 is determined by the control unit 141 in accordance with the laundry amount of the selected course before the water supply step 212. In this exemplary embodiment, when the centrifugal washing course is selected, the desired water level may be lower than that of the ordinary washing course in the water supply step 212. The desired water level is a little lower than the drum 124 in the water supply step 212 and may be the minimum amount for washing water to be able to circulate in the centrifugal washing step 216.

In the water supply step 212, the amount of washing water flowing in the tub 122 is determined through the flowmeter 142. The amount of washing water in the tub 122 cannot be measured by the water level sensor 121 because the desired water level is too low in the water supply step 212, so the control unit 141 calculates the amount of washing water flowing in the tub 122 from the flow rate of washing water measured by the flowmeter 142.

When washing water flows in the tub 122 up to the desired water level, the control unit 141 finishes the water supply step 212 by stopping the water supply unit 131 and performs a laundry wetting step 213.

The laundry wetting step 213 is a step of rotating the drum 124 by operating the driving unit 113 with the control unit 141 so that washing water mixed with a washing detergent uniformly wets laundry and the washing detergent is dissolved.

In the laundry wetting step 213, the control unit 141 rotates the drum 124 and operates the pump 136, thereby circulating the washing water in the tub 122. As the control unit 141 sends the washing water in the tub 122 to the circulating hose 137 under pressure by operating the pump 136, the washing water is circulated along the circulating hose 137 and sprayed into the drum 124 through the circulating nozzle 139.

Depending on exemplary embodiments, when the washing water is sprayed into the drum 124 through the circulating nozzle 139 in the laundry wetting step 213, the control unit 141 can make washing water be sprayed into the drum 124 through the spray nozzle 151 by making the washing water supplied from the external water source through the fourth water supply hose 131 d flow to the spray nozzle 151 by controlling the water supply unit 131. In the laundry wetting step 213, the control unit 141 may intermittently operate the water supply unit 131 so that washing water is intermittently sprayed through the spray nozzle 151.

In the laundry wetting step, the control unit 141 may rotate the drum 124 such that the laundry in the drum 124 rolls on the bottom of the drum 124 by controlling the driving unit 113.

When the laundry is wetted by washing water in the laundry wetting step 213, the amount of the washing water in the tub 122 reduces.

The control unit 141 rotates the drum 124 by controlling the driving unit 113 for a predetermined time and circulates the washing water by controlling the pump 136, thereby performing the laundry wetting step 213, and when a predetermined time passed, the control unit 141 stops the drum 124 by stopping the driving unit 112 and stops the pump 136, thereby finishing the laundry wetting step 213. The control unit 141 performs a steam step 214 after finishing the laundry wetting step 213.

The steam step 214 is a step of spraying steam into the drum 124. In the steam step 214, the control unit 141 makes washing water be supplied to the steam unit 145 through the fifth water supply hose 131 e by controlling the water supply unit 131. The control unit 141 generates steam by heating the supplied washing water, by operating the steam unit 145. The steam generated by the steam unit 145 is sprayed into the drum 124 through the steam nozzle 152.

Depending on exemplary embodiments, the supply of washing water to the steam unit 145 by controlling the water supply unit 131 with the control unit 141 may be performed in the water supply step 212 or the laundry wetting step 213 before the steam step 214.

In the steam step 214, the high-temperature steam sprayed into the drum 124 increases the temperature of the laundry in the drum 124 and the washing water in the tub 122. The amount of washing water supplied in the tub 122 in the water supply step 212 is small and it is difficult to heat the washing water with the heater 143, so the washing performance is improved by increasing the temperature of the washing water in the tub 122 by spraying steam.

Depending on exemplary embodiments, the control unit 141 can rotate the drum 124 by controlling the driving unit 113 in the steam step 214.

The control unit 141 makes steam be sprayed into the drum 124 by controlling the steam unit 145 for a predetermined time, and when a predetermined time passed, it stops the steam from being sprayed into the drum 124 by stopping the steam unit 145.

The balancing step 215 is a step of balancing the balancer 126 and the laundry in the drum 124 by rotating the drum 124 at a high speed. The balancing is to minimize vibration and noise by making the rotation center of the drum 24 rotating close to the center of gravity of the drum 124 with laundry therein.

In the balancing step 215, the control unit 141 accelerates the drum by operating the driving unit 113 and maintains a predetermined speed. The control unit 141 rotates the drum 124 at a constant speed and determines whether balancing is made on the basis of the actual rotation speed of the drum 124 measured by the driving unit 113.

A method of determining whether balancing is made, by the control unit 141 is described below with reference to FIG. 8.

In the balancing step 215, the control unit 141 may rotate the drum 124 faster than the maximum speed of the drum 124 in the laundry wetting step 213 by controlling the driving unit 113. In the balancing step 215, the constant rotation speed of the drum 124 may be a speed at which laundry attachs on the drum 124 and may be smaller than the speed in an excessive resonance range. The resonance range is a rotation speed range of the drum 124 in which vibration due to rotation of the drum 124 is matched with the natural frequency of the washing machine 100, thereby generating resonance, so the drum 124 may be rotated out of the resonance range. In this exemplary embodiment, the drum 124 rotates at 130 rpm in the balancing step 215.

The control unit 141 performs the centrifugal washing step 216 by accelerating the drum 124, when balancing is achieved in the balancing step 215.

The centrifugal step 216 is a step of spraying the circulating washing water into the drum 124 rotating at a high speed. In the centrifugal washing step 216, the control unit 141 accelerates the drum 124 and maintains a predetermined speed, and operates the pump 136, thereby circulating the washing water in the tub 122.

In the centrifugal washing step 216, the control unit 141 rotates the drum 124 faster than the maximum speed of the drum 124 in the balancing step 215. In the centrifugal step 216, the drum 124 may rotate such that laundry attachs on the drum 124, and the drum 124 rotates at 380 rpm in this exemplary embodiment.

In the centrifugal washing step 216, the control unit 141 rotates the drum 124 at a predetermined speed and sends the washing water in the tub 122 to the circulating hose 137 under pressure by operating the pump 136. In the centrifugal washing step 216, the washing water circulates through the circulating hose 137 and is sprayed into thee drum 124 rotating at a high speed through the circulating nozzle 139.

In the centrifugal washing step 216, the pump 136 may circulate the washing machine by keeping operating for a predetermined time, and the pump 136 may intermittently operate, depending on exemplary embodiments.

Depending on exemplary embodiments, in the centrifugal washing step 216, the control unit 141 can make washing water be sprayed into the drum 124 through the spray nozzle 151 by making the washing water supplied from the external water source through the fourth water supply hose 131 d flow to the spray nozzle 151 by controlling the water supply unit 131. In the centrifugal washing step 216, the control unit 141 may intermittently operate the water supply unit 131 so that washing water is intermittently sprayed through the spray nozzle 151.

The control unit 141 rotates the drum 124 by controlling the driving unit 113 for a predetermined time and circulates the washing water by controlling the pump 136, thereby performing the centrifugal washing step 216, and when a predetermined time passed, the control unit 141 stops the drum 124 by stopping the driving unit 112 and stops the pump 136, thereby finishing the centrifugal washing step 216. Depending on exemplary embodiments, the control unit 141 stops the washing water from being sprayed, by stopping the operation of the water supply unit 131, when the centrifugal washing step 216 is stopped. The control unit 141 performs the draining step 217 after finishing the centrifugal washing step 216.

The draining step 217 is a step of discharging the washing water in the tub 122 to the outside of the cabinet 111. In the draining step 217, the control unit 141 operates the pump 136 such that the washing water in the tub 122 is discharged outside through the drain hose 138. In the draining step 217, the drum 124 may be stopped, but the control unit 141 may rotate the drum1 124 by operating the driving unit 113, depending on exemplary embodiments.

Further, depending on exemplary embodiments, it may be possible to perform the draining step 217 with the drum 124 rotating at a high speed, without stopping the driving unit 113, when the centrifugal washing 216 is finished.

After the draining step 217, a spinning step in which the drum 124 rotates at a high speed so remove the washing water from laundry may be performed, or general washing step or rinsing step may be performed after a general water supply step is performed again.

FIG. 7 is a partial detailed block diagram illustrating the washing machine according to an exemplary embodiment of the present invention.

The driving unit 113 of a washing machine according to an exemplary embodiment of the present invention includes a motor 113 a rotating the drum 124 and a speed detector 113 b sensing the actual rotation speed of the drum 124. The control unit 141 of a washing machine according to an exemplary embodiment of the present invention includes a low band filter 141 a that passes a low band part of a rotation speed value sensed by the speed detector 113 b and a balancing unit 141 b that controls the motor 113 a to accelerate the drum 124, when the value when the low band filter 141 a is applied is an acceleration time point value.

The motor 113 a, which generates rotational force by receiving power, includes a rotor (not shown) and a stator (not shown).

The speed detector 113 b detects the rotation speed of the rotor (not shown) and senses the actual rotation speed of the drum 124, using a hole sensor or other sensing devices. Even if the motor 113 a rotates the drum 124 at a constant speed, the actual rotation speed of the drum 124 is not constant and has a little fluctuation due to unbalance of the drum 124. The speed detector 113 b senses the actual rotation speed of the drum 124 and outputs the rotation speed value by sensing the rotation speed of the rotor (not shown) connected with the drum 124.

The low band filter 141 a passes the low band part of the rotation speed value sensed by the speed detector 113 b. The larger the fluctuation of the rotation speed value, the smaller the value when the low band filter 141 a is applied (hereafter, “low band filter-applied value), and the larger the fluctuation, larger the low band filter (141 a)-applied value. The boundary value of the passing band of the low band filter 141 a may depend on the amount of laundry in the drum 124, and the larger the amount of laundry, the larger the boundary value, and the smaller the amount of laundry, the smaller the boundary value.

The balancing unit 141 b controls the motor 113 a to accelerate the drum 124, when the low band filter (141 a)-applied value is the acceleration time point value. The acceleration time point value, which shows the point of time when the balancer 126 and the laundry in the drum 124 are appropriately balanced, is a value between the maximum and the minimum of the low band filter (141 a)-applied value. When the drum 124 is accelerated and rotated at a high speed at the acceleration time point value, vibration and noise of the drum 124 can be minimized.

The balancing unit 141 b accelerates the drum 124, when the value when the low band filter 141 a is applied is an acceleration time point value, before it reaches the maximum value over the minimum value. An appropriate acceleration time point value is a time point after the minimum value and before the maximum value, in the values between the minimum value and the maximum value.

In the exemplary embodiment, the balancing unit 141 b accelerates the drum 124, when the low band filter (141 a)-applied value is the acceleration time point value, and the control unit 141 performs the centrifugal washing step 216.

FIG. 8 is a partial detailed flowchart illustrating a method of controlling a washing machine according to an exemplary embodiment of the present invention and FIG. 9 is a view showing a change in actual rotation speed of a drum and the result of applying a low band filter in the method of controlling a washing machine illustrated in FIG. 8.

The motor 113 a rotates the drum 124 at a predetermined distance (S310). For balancing, the motor 113 a rotates the drum 124 at a predetermined speed and the predetermined speed may be a speed at which laundry attachs on the drum 124 and may be smaller than the speed in an excessive resonance range. In this exemplary embodiment, the motor 113 a rotates the drum 124 at 130 rpm.

The speed detector 113 b senses the actual rotation speed of the drum 124 (S320). The speed detector 113 b detects the rotation speed of the rotor (not shown) and senses the actual rotation speed of the drum 124, using a hole sensor or other sensing devices.

Referring to (a) of FIG. 9, even if the motor 113 a rotates the drum 124 at a constant speed, the actual rotation speed of the drum 124 is not constant and has a little fluctuation due to unbalance of the drum 124. The speed detector 113 b senses the actual rotation speed of the drum 124 and outputs the rotation speed value by sensing the rotation speed of the rotor (not shown) connected with the drum 124.

The low band filter 141 a is applied to the sensed rotation speed value (S330). As shown in (a) of FIG. 9, the boundary value of the passing band of the low band filter 141 a may depend on the amount of laundry in the drum 124, and the larger the amount of laundry, the larger the boundary value, and the smaller the amount of laundry, the smaller the boundary value. When the low band filter 141 a is applied to the rotation speed value, the larger the fluctuation of the rotation speed value, the smaller the low band filter (141 a)-applied value, and the smaller the fluctuation, the larger the low band filter (141 a)-applied value, as in (b) of FIG. 9.

The balancing unit 141 b determines whether the low band filter (141 a)-applied value is an acceleration time point value B before the maximum value over the minimum value m (S340). The acceleration time point value B is a time point after the minimum value and before the maximum value, in the values between the minimum value and the maximum value, and when the drum 124 is accelerated and rotated at a high speed at the acceleration time point value B, vibration and noise of the drum 124 can be minimized.

When the low band filter (141 a)-applied value is the acceleration time point value B before the maximum value over the minimum value m, the balancing unit 141 b accelerates the drum 124 by controlling the motor 113 a (S350). The balancing unit 141 b accelerates the drum 124, when the low band filter (141 a)-applied value is the acceleration time point value, and the control unit 141 performs the centrifugal washing step 216.

Although exemplary embodiments of the present invention are illustrated and described above, the present invention is not limited to the specific exemplary embodiments and may be modified in various ways by those skilled in the art without departing from the scope of the present invention described in claims, and the modified examples should not be construed independently from the spirit or the scope of the present invention.

According to a washing machine and a method of controlling the washing machine of an exemplary embodiment of the present invention, one or more effects can be achieved as follows.

First, it is possible to reduce use of water by minimizing washing water supplied to the tub, when water is supplied.

Second, it is possible to increase the temperature of washing water with relatively less energy and improve washing performance by spraying steam into the drum after washing water is supplied to the tub.

Third, it is possible to reduce the washing time and improve washing performance by spraying circulating washing water with the drum rotating at a high speed.

Fourth, it is possible to reduce the washing time by efficiently performing balancing with the balancer, before the drum rotates at a high speed.

Fifth, it is possible to improve washing performance by spraying washing water, which is supplied from the external water source, into the drum rotating at a high speed.

The effects of the present invention are not limited to those described above and other effects not stated herein may be made apparent to those skilled in the art from claims. 

What is claimed is;:
 1. A method of controlling a washing machine, comprising: a water supply step of supplying washing water into a tub; a steam step of spraying steam into a drum disposed in the tub; and a centrifugal washing step of circulating the washing water in the tub and of rotating the drum such that laundry attachs to the drum.
 2. The method of claim 1, wherein in the water supply step, the amount of washing water flowing into the tub is smaller than the amount of washing water in ordinary washing.
 3. The method of claim 1, wherein in the water supply step, the amount of washing water flowing into the tub is the minimum amount that can circulate washing water in the centrifugal washing step.
 4. The method of claim 1, wherein in the water supply step, the level of the washing water flowing in the tub is lower than the drum.
 5. The method of claim 1, further comprising a balancing step of balancing a balancer and the laundry by accelerating the drum such that the laundry attachs to the drum.
 6. The method of claim 5, wherein the centrifugal washing step rotates the drum at a higher speed than the balancing step, by accelerating the drum in the balancing step.
 7. The method of claim 1, further comprising a laundry wetting step of wetting laundry in the drum by circulating the washing water in the tub and rotating the drum, after the water supply step.
 8. The method of claim 1, wherein washing water supplied from an external water source is sprayed into the drum in the centrifugal washing step.
 9. The method of claim 8, wherein washing water supplied from the external water source is intermittently sprayed in the centrifugal washing step.
 10. A washing machine comprising: a tub that receives washing water; a drum that is disposed in the tub and rotates with laundry therein; a driving unit that rotates the drum;a water supply unit that adjusts inflow of washing water from an external water source; a steam unit that generates steam and sprays the steam into the tub; a pump that pumps out the washing water in the tub and circulates the washing water into the tub; and a control unit that controls the driving unit, the water supply unit, and the pump, wherein the control unit performs: a water supply step of supplying washing water into the tub by operating the water supply unit; a steam step of spraying steam into the drum by operating the steam unit; and a centrifugal washing step of rotating the rum such that laundry attachs to the drum by operating the driving unit and of circulating the washing water in the tub by operating the pump.
 11. The washing machine of claim 10, wherein the control unit controls the water supply unit such that the amount of washing water flowing into the tub is smaller than the amount of washing water in ordinary washing, in the water supply step.
 12. The washing machine of claim 10, wherein the control unit controls the water supply unit such that the amount of washing water flowing into the tub becomes the minimum amount that can circulate the washing water in the tub, in the water supply step.
 13. The washing machine of claim 10, wherein the control unit controls the water supply unit such that the level of the washing water flowing in the tub is lower than the drum.
 14. The washing machine of claim 10, further comprising a balancer that balances laundry in the drum, wherein the control unit rotates the drum by operating the driving unit and balances the balancer with the laundry, after the steam step.
 15. The washing machine of claim 14, wherein the control unit performs a centrifugal step by rotating the drum at a higher speed than the balancing step by accelerating the drum, by operating the driving unit after balancing the balancer with the laundry.
 16. The washing machine of claim 10, wherein the control unit performs a laundry wetting step of wetting laundry in the drum, by rotating the drum by operating the driving unit, and by circulating washing water in the tub by operating the pump, after the water supply step.
 17. The washing machine of claim 10, further comprising a spray nozzle that is connected with the water supply unit and sprays washing water supplied from an external water source into the drum, wherein the control unit makes washing water supplied from an external water source be sprayed into the drum through the spray nozzle by operating the water supply unit in the centrifugal washing step.
 18. The washing machine of claim 17, wherein the control unit intermittently operates the water supply unit so that washing water is intermittently sprayed in the centrifugal washing step. 